Amplifying you hand movement is the basic function of a lever. In this case it isn't desired. When you pick up something with tweezers you don't even notice the hand shaking. Until you look under a microscope at the pcb you are trying to populate. Then you look like you have Parkinson's or another muscle problem. Indecently the first place I worked with surface mount we made a implantable device that would stop the tremors from Parkinson's. With the suction device it is much better because the lever is shorter and you don't need as much finger flexion. This gives you less shaking transfer. Plus you can roll the bulb between your finger and thumb to rotate the chip. Not and easy thing to do with tweezers. Still you need to be calm and take your time. That is why the company I used to work for shelled out the one million dollars for a pick-place machine. It was amazing how fast it could populate boards. Even with the smallest resistors. Then the boards went right an oven on a conveyor.
When you put your boards on the hot plate do you have something overtop to reflect the heat back down? I think this would be better because the heat would surround the paste making melt faster. That way the chips aren't heated for as long.
Wayne
From: "Michael Hawkins korgpolyex800@... [korgpolyex]" <korgpolyex@yahoogroups.com>
To: "korgpolyex@yahoogroups.com" <korgpolyex@yahoogroups.com>
Sent: Monday, June 6, 2016 9:12 AM
Subject: Re: [korgpolyex] AtomaHawk - new hardware version in final testing
To: "korgpolyex@yahoogroups.com" <korgpolyex@yahoogroups.com>
Sent: Monday, June 6, 2016 9:12 AM
Subject: Re: [korgpolyex] AtomaHawk - new hardware version in final testing
Thanks Wayne, coincidentally,
I ordered a couple of those last night. I use a fixture jig for placing
the board and orienting it to a kaptan stencil overlaid for applying the solder paste. I
then use tweezers which is by far the hardest part (especially with the
tiny AD5290). I then place on a hot plate, using a laser temperature
sensor and visually watching for the solder to run. I take the board off
using tweezers, I
found that applying the solder paste in the right quantities and
consistently across all solder pads is tricky. But that is something
that gets better with practice. And most importantly, if it isn't perfect, wipe off the paste, clean the board and stencil, and do it over until you get it perfect.
And then
the really hard part is placing really small SMD footprints such as
MSOP. Tweezers make the job quite awkward and I realized that is because
they don't help you to line up the device radially/rotational at all
and they also amplify your hand natural shaking movements. So a suction tool and a arm/wrist bench/rest are critically important.
It's
been a lot of fun going through the learning experience and it has now
completely revolutionized my view of designing and building surface
mounted designs. Especially with the STM32 upgrade in mind.
/Mike
From: "Wayne atlas1301962@... [korgpolyex]" <korgpolyex@yahoogroups.com>
To: "korgpolyex@yahoogroups.com" <korgpolyex@yahoogroups.com>
Sent: Sunday, June 5, 2016 10:09 PM
Subject: Re: [korgpolyex] AtomaHawk - new hardware version in final testing
To: "korgpolyex@yahoogroups.com" <korgpolyex@yahoogroups.com>
Sent: Sunday, June 5, 2016 10:09 PM
Subject: Re: [korgpolyex] AtomaHawk - new hardware version in final testing
The places I worked at that had surface mount components we didn't use tweezers most of the time. We had little suction cups with bulbs on them. You squeezed the bulb then put the cup on the component. Releasing the bulb then cause a vacuum that held the component. It was like attaching a handle to the chip. You can buy kits that have several sizes for different size chips. Much better than tweezers and less work than a jig.
Wayne
From: "Michael Hawkins korgpolyex800@... [korgpolyex]" <korgpolyex@yahoogroups.com>
To: "korgpolyex@yahoogroups.com" <korgpolyex@yahoogroups.com>
Sent: Sunday, June 5, 2016 8:50 PM
Subject: Re: [korgpolyex] AtomaHawk - new hardware version in final testing
To: "korgpolyex@yahoogroups.com" <korgpolyex@yahoogroups.com>
Sent: Sunday, June 5, 2016 8:50 PM
Subject: Re: [korgpolyex] AtomaHawk - new hardware version in final testing
Ha ha! Yes, I was very pleasantly surprised at how easy it is. I am actually kicking myself for not having tried surface mount ten years ago. Stupid really. But I guess you get used to what you're doing and sometimes you don't want to change what works.
But in this case, going to surface mount has some challenges but they can all be overcome. As long as the board isn't too big or uses the really small SMD components.
The AD5290 is a TSSOp which is very small to handle with tweezers. It can be positioned but it is really difficult. So I am making a jig that will help me to place it. I shall let you know how that goes.
But as always Gordon, your questions are always a strong indication of your insight. So why the heck didn't you tell me to try SMD earlier? Eh?
/Mike
From: "Gordonjcp gordon@... [korgpolyex]" <korgpolyex@yahoogroups.com>
To: "Michael Hawkins korgpolyex800@... [korgpolyex]" <korgpolyex@yahoogroups.com>
Sent: Sunday, June 5, 2016 6:07 PM
Subject: Re: [korgpolyex] AtomaHawk - new hardware version in final testing
To: "Michael Hawkins korgpolyex800@... [korgpolyex]" <korgpolyex@yahoogroups.com>
Sent: Sunday, June 5, 2016 6:07 PM
Subject: Re: [korgpolyex] AtomaHawk - new hardware version in final testing
On Sun, Jun 05, 2016 at 03:45:14PM +0000, Michael Hawkins korgpolyex800@... [korgpolyex] wrote:
> So, I went looking for a new through hole chip that could be used but alas I was completely unable to find one. What I did find was a far better device but it is only available in surface mount. I finally had to go through the process of figuring out how hard (or not) it is to create surface mount boards in small quantities.
... and you found it's actually way, way easier than through-hole?
--
Gordonjcp MM0YEQ